Impulse transmitter



Sept. 5, 1939. H. E. MALI ET AL IMPULSE TRANSMITTER Filed Jan. 6, 1938 Patented Sept. 5, i939 Electric Company, Incorporated,- N. Y., a corporation Application January 6,

son, Clarendon 9Claims.

This invention relates to impulse transmitters, and more particularly to an impulse transmitter for use in the calling dial in an automatic telephone system.

It is an object of the present invention to provide a quiet and simple mechanism for transmitting impulses.

In accordance with one embodiment of the invention, there is provided an impulse pawl adapted to be actuated by a dial controlled cam wheel for opening and closing a pair' of contacts to transmit impulses and having a pair of flat portions formed thereon disposed at angles'one to another for cooperation with an inverted V- shaped leaf spring which normally tends to hold the pawl in either of two adjusted positions, whereby, upon manual operation of the dial in a clockwise direction, the pawl may be moved only a short distance and will not snap back against the succeeding tooth of the cam wheel and whereby, upon the return -of'the cam wheel to normal position in a counter-clockwise direction, the other flat portion of the pawl will engage a V- spring to prevent thepawl from slapping against the teeth of the cam wheel, thereby eliminating a great deal of undesirable noise incident to the operation of the dial.

A better understanding will be had of the in-. vention by. reference to the accompanying draw-:

0 ing, whereim,

Fig. 1 shows a front elevational view of a telephone dialing mechanism, parts being broken away to show more clearly the portions of the mechanism with which the present invention is .85 concerned;

Fig. 2 shows a rear view of the dialing mechanism shown in Fig. 1;

Fig. 3 is an enlarged fragmentary view of a portion of the apparatus shown in Fig. 1 illus- 40 trating the construction of the pawl and its associated mechanism;

Fig. 4 is a sectional view taken substantially along the line 4-4 of Fig. 3 in the direction of the arrows; and r Fig. 5 is a sectional view taken substantially along the line 55 of Fig. 3 in the direction of the arrows.

Referring now to the drawing, wherein like reference numerals designate the same .parts 50 throughout the several views, the numeral Ill designates a dialfor use in an automatic telephone transmitting apparatus provided with a series of finger apertures I I, whereby the dial may be rotated inra clockwise direction until the 5s finger of the person operating the dial engages a New York, ofNewYorlr- 1938, No. 183.814 (Cl. 179-90) stop H2. The dial is of the type common to telephone dialing apparatus, and upon its release, will be driven in a counter-clockwise direction by a spring motor (not shown), a suitable governor l3 being provided for controlling the speed of the dial in its return to normal position. 'The dial I0 is secured to a shaft l4 bymeans of a nut l5 threaded onto the end of the shaft. Carried by the shaft I4 is an impulse wheel or cam wheel It having one wide tooth H and a seriu of ten small teeth I 8 formed about its periphery. The stop I2 is fixedto a cup-shaped casing 2| which encloses the operating parts of the dialing mechanism. This mechanism includes an abutment 22 against which the spring motor (not shown) will urge a stop member 20 fixed to the shaft ll. The apparatus thus far described is the apparatus common to telephone dials in general use at the present time for actuating an impulse transmitter to send impulses for indicating the telephone number to which it is desired to be connected.

In accordance with the present invention, a pawl, designated generally-by the numeral 22, and adapted to be actuated by the teeth l8 of the cam wheel or impulse wheel It, has a portion 24 which extends into the path of the teeth II on the cam wheel l6 so that during rotation of the cam wheel, the teeth It will move the pawl 23, which is pivotally mounted between a bracket 25 securedto the casing 2! by screws 28, and a bracket 21 formed integrally with the casing 2|. The pawl 23 is fixed to a pivot pin 28, which is mounted in apertures and II formed in the brackets 25 and 21, respectively. A portion 33 of the pawl 23 extends through the rear portion of the casing 2i and carries a tubular insulator 34 on a reduced portion 35 thereof, which, when the dial i I is' moved in a clockwise direction (Fig. 1), will be moved away from a contact spring 21 normally engaging a fixed contact 38. Both the contact spring 31 and fixed contact 38 form part of a spring pile-up 39 which controls the transmission of impulses for connecting a telephone subscriber with another subscriber through automatic or semi-automatic telephone exchanges. The operation of those springs in the pile-up 39, other than the contact spring 31 and fixed contact 38, does not relate to the present invention and a detailed description thereof, accordingly. will not be given. 7

Upon the rotation of the cam wheel I! and dial H in a counterclockwise direction (Fig. 1), the portion 24 of the pawl 23 will he -moved by each of the teeth l8 which had been moved past it during the clockwise rotation of the dial to tween spring 37. andrfixed contact @ch time a tooth l8 under the portion 24 of the pawl. Portions 4d andti oi the pawl 23 are bent 'over at right angles to the main body of the pawl for receiving the pin 28, and the bent over portion 4| the left end thereof (Figs. 1, 3 and 4) extended to the left beyond the body ofthe pawl to provide a pair offiat surfaces 42 and 43 (Fig. 3) angularly disposed one to another for out by a spring designated generally by the numeral 44. The spring 44 has a body portion 48 secured to the casing 21 by means of screws 46 and has a portion i1 bent at right angles to the body portion 45. The portion 41 of the spring 44 has a pawl engaging portion 4! formed integrally therewith and bent at an angle thereto and normally urged to the right (Figs. 1, 3 and 4) into engagement with the fiat portion 42 and 48 of the pawl. The portion 48 of the spring 44 is squeezed together to form a substantially V-shaped cross section in the pawl engaging portion of the spring whereby when the pawl 23 is rocked in a counter-clockwise direction about its pivot 28, the fiat surface 42 of the pawl will be urged to stay in a position where the portion 24 of the pawl will just barely engage with the teeth I8, which are moved past the pawl during further clockwise rotation (Fig. 1) of the dial ll. Similarly, when the dial is released and automatically returns to position to bring the stop member 2ll into engagement with the abutment 22, the portion 26 of the pawl will, upon the passage of the first tooth it past it in a counter-- clockwise direction, bring the flat surface 43 into engagement with the V-shaped portion of the spring 44, which will normally urge the pawl to stay in a position where the portion 24 will just engage the teeth i8 and will be moved by the teeth l8 only slightly more than the pawl was moved during the rotation of the dial ii in a clockwise direction, but sufilcient' to cause the insulator 34 mounted on the pawl to open the circuit between contact spring 3'5 and fixed contact 38 each time one of the teeth it passes the pawl 23 during its counter-clockwise rotation (Fig. 1).

The provision of the spring 44 with a V-shaped construction at the point thereof where it engages the flat surfaces 42 and G3 on the pawl will, after the initial movement of the pawl in either a clockwise or counter-clockwise direction, tend to hold the pawl in position where it will be engaged only slightly by the teeth l8 during their. movement and the portion 24 of the pawl 23 will therefore not slap against the next succeeding tooth, whereby the undesirable noise incident to dialing operations is substantially reduced. The V-shaped portion of the spring 44 will also hold the pawl 23 at the proper level to cause the portion 24 to engage the'teeth GB of the cam wheel it, thereby simplifying the assembling of the parts and making the apparatus cheaper to construct.

specific method of mounting the pieces of appa-' ratus which contribute to-the reduction of the noise of operation of the dial have been given, it will be understood that the apparatus is sub- 'iect to numerous modifications without departing from the scope of the invention, which is to be limited only by the scope of the appended claims.

What is claimed is:

1. In an impulse-transmitting device, a rotat- I hold the pawl in either of two predetermined positions in one plane and in a predetermined position in another plane.

2. In an impulse transmitting device, a rotatable dial. a cam wheel fixed to said dial, a pawl having a portion thereof extending into cooperative relation with said cam wheel for operation thereby and having another portion provided with cam faces, and a spring positioned to engage said cam faces in diiferent positions of said pawl and formed to hold a portion of the pawl in the plane of the cam wheel.

3. In an impulse transmitting device, a rotatable dial and cam wheel fixed to said dial and having a plurality of camming projections, a pawl having a portion thereof extending into the path of said camming projections, means for urging said pawl into a predetermined position upon the rotation of the dial in one direction, and means for urging the pawl into another position upon the rotation of the dial in the opposite direction, saidlast two mentioned means being a spring having two portions for performing these operations and being constructed to hold the cam wheel engaging portion of the pawl in the plane of the cam wheel.

4. In an impulse transmitting device, a rotatable dial, a cam wheel secured to said dial having a plurality of camming projections, a pawl having a portion thereof extending into the path of said camming projections, a spring engaging said pawl, and means formed on said pawl for cooperation with said spring tending to hold the pawl in one position on rotation of the dial in one direction and tending to hold the pawl in another position onrotation of the dial in the opposite direction in one plane and for holding the pawl in a predetermined plane.

5. In an impulse transmitting device for automatic telephone system, a pair of normally closed contacts, and means operable to open said contacts including a cam wheel having a plurality of camming projections, a pawl having a portion thereof extending into the path of said camming projections, means for pivotally supporting said pawl, a pair of angularly disposed flat surfaces formed on said pawl, and a spring adapted to engage both edges of said surfaces in either of two positions of said pawl.

6. In an impulse transmitting device for automatic telephone system, a pair of normally closed contacts, means operable to open said contacts a selected number of times, including a pawl having a portion adapted to engage one of said contacts, a cam wheel associated with said pawl for actuating it a selected number of times, and a V-shaped spring associated with said pawl for tending to hold it in one position during the rotation of the cam wheel in one direction and for tendingto hold it in another position during rotation of the cam wheel in the opposite direction.

'I. In an impulse transmitting device for automatic telephone systems, a contact actuating pawl, a cam wheel associated with said pawl for actuating it, means on said pawl for engaging portions of said camming wheel, a pair of flat surfaces formed on a portion of said pawl, and a leaf spring having a V-shaped portion associated with the flat surfaces on the I said pawl for normally tending to hold the pawl in either of two positions upon engagement of the pawl with said portions of the camming wheel.

8. In an impulse transmitting device for automatic telephone systems, a contact actuating pawl, a cam wheel associated with said pawl for actuating it, means on said pawl for engaging portions of said camming wheel, a pair of fiat surfaces formed on a portion of said pawl, and a leaf spring having a V-shaped portion associated with the flat surfaces on said pawl for normally tending to hold the pawl in either of two positions upon engagement of the pawl with said portions of the camming wheel, depending upon the direction of movement of said camming 15 wheel.

9. In an impulse transmitting device for automatic telephone systems, a contact actuating pawl, a cam wheel associated with said pawl for actuating it, means on said pawl for engaging portions'of said camming wheel, a pair of flat surfaces formed on a portion of said pawl, a leaf spring having a V-shaped portion associated with the flat surfaces on said pawl for normally tending to hold the pawl in either of two positions upon engagement of the pawl with said portions of the camming wheel, depending upon the direction of movement of said camming wheel, and for holding the pawl in a predetermined plane.

HARRY E. MALI. PAUL G. FREDRICKSON. 

